1. Technical Field
This disclosure relates generally to a fastening assembly and components of the fastening assembly and, more particularly, to a structural fastener assembly and components of such a fastening assembly, which maybe for attaching a cover or panel to a substructure, particularly in high stress environments.
2. Related Art
A variety of fastener assemblies are known for attaching a panel to a substructure, for example, such as attaching a panel to an aircraft structure. Such fastening assemblies are typically designed for use in high stress environments, such as to protect aircraft access panels, and when used in such environments, are referred to as structural fasteners or structural fastening assemblies. Such structural fastening assemblies must be able to maintain secure attachment of the panel to the substructure panel during conditions of excessive vibration and high loads applied to the panel during flight.
The studs of captive fastening assemblies remain captive in the stud assembly when the panel is removed. Therefore, when the panels are removed from the substructure, the studs remain with the cover, maintaining the position of the studs relative to the panel and eliminating the problem of stud loss or displacement. In general, the studs of captive fastening assemblies only can be extended from the stud assembly to one position. This is problematic when the clearance required to remove a panel is minimal. In such situations, the studs must be removed from the fastening assembly, which is problematic because it is easy to lose, drop and confuse the studs, and thereafter it is difficult to tell which fasteners the studs belong to when reattaching the panel to the substructure. One way this has been addressed is to use studs of varying length so that the amount of stud exposed underneath the panel after the stud is extended can be varied.
Many existing captive fastening assemblies are also quite delicate and are unable to withstand the force associated with the use of pneumatic drills, which increases the amount of time required to remove and re-install panels. Some fastening assemblies have reduced life due to breakage of retaining rings, as well as other components of the assemblies. When the retaining ring breaks, depending on the design of the fastener, it often may result in the screw or stud falling out of the assembly, defeating the purpose of using a “captive” fastener assembly. Another common type of failure is due to “foreign object debris” (FOD), which is common in fastening assemblies that include a hole in the stud or screw which becomes filled with debris over time.